CN112531125A

CN112531125A - Organic light emitting diode and device having the same

Info

Publication number: CN112531125A
Application number: CN202011242616.1A
Authority: CN
Inventors: 丁勇升; 王禹清; 林意惠
Original assignee: AU Optronics Corp
Current assignee: AU Optronics Corp
Priority date: 2020-04-30
Filing date: 2020-11-09
Publication date: 2021-03-19
Anticipated expiration: 2040-11-09
Also published as: US10862064B1; TWI749782B; TW202143475A; SG10202005976SA; DE102020126803A1; CN112531125B

Abstract

An Organic Light Emitting Diode (OLED) display panel includes a substrate, a light reflecting electrode layer on the substrate, and a Pixel Definition Layer (PDL) formed on the substrate and the light reflecting electrode layer. The light reflecting electrode layer has a plurality of light reflecting structures, and each light reflecting structure has a first region and a second region. The pixel defining layer is provided with a plurality of openings with respect to the light reflecting structures such that the first and second regions of each light reflecting structure are exposed in the corresponding opening thereof. A plurality of organic light emitting structures are correspondingly formed in the openings and cover the light reflecting structures to form a plurality of pixels. For each corresponding pixel in the pixels, a first light reflectance corresponding to the first region in the corresponding pixel is greater than a second light reflectance corresponding to the second region in the corresponding pixel.

Description

Organic light emitting diode and device having the same

Technical Field

The present disclosure relates to display technologies, and more particularly, to a method for fabricating a high resolution Active Matrix Organic Light Emitting Diode (AMOLED) panel.

Background

The background description provided herein is for the purpose of generally presenting the disclosure. The inventors hereby give notice that it is believed that the present disclosure, including what is described in the background section hereof, is not entitled to antedate such disclosure by virtue of prior art, nor is it intended to be exhaustive or to imply that all such prior art would be inferred by the present disclosure.

Organic Light Emitting Diode (OLED) display panels are widely used in mobile devices such as mobile phones or tablet devices. In some examples, the OLED display panel may be an active matrix OLED (amoled) display panel used in devices requiring high resolution, such as in a Virtual Reality (VR) device. As the resolution of the OLED display panel increases, the size of each light emitting structure of the light emitting layer in the OLED display panel becomes smaller, making precise coating alignment for the light emitting structure more difficult.

Thus, the above-described deficiencies and inadequacies have heretofore not been addressed in the art.

Disclosure of Invention

The present disclosure relates to an Organic Light Emitting Diode (OLED) display panel, comprising: the light-emitting device comprises a substrate, a light-reflecting electrode layer arranged on the substrate and a plurality of light-reflecting structures, wherein each light-reflecting structure comprises a first area and a second area, and a Pixel Defining Layer (PDL) formed on the substrate and the light-reflecting electrode layer, the pixel defining layer is provided with a plurality of openings corresponding to the light-reflecting structures, so that the first area and the second area of each light-reflecting structure are exposed in one corresponding opening, and a plurality of organic light-emitting structures which are correspondingly formed in the openings and cover the light-reflecting structures form a plurality of pixels, wherein in each corresponding pixel, a first light-reflecting rate of each pixel corresponding to the first area is greater than a second light-reflecting rate of each pixel corresponding to the second area.

In some present embodiments, the OLED display panel has an overall light reflectance of greater than or equal to 80%.

In some present embodiments, a first area ratio, i.e., X, is a ratio of the first area to the total area of each light reflecting structure, a second area ratio, i.e., (1-X), is a ratio of the second area to the total area of each light reflecting structure, and X is greater than or equal to 80% and less than or equal to 99%.

In some embodiments, the difference between the first area ratio of the first area and the second area ratio of the second area is greater than or equal to 1%.

In some embodiments, the first region and the second region are formed of the same material and have different thicknesses, such that a first light reflectivity of the first region is greater than a second light reflectivity of the second region.

In some embodiments, the material is selected from a group consisting of silver (Ag), aluminum (Al), magnesium (Mg) and molybdenum (Mo), and a first thickness of the first region is greater than a second thickness of the second region.

In some embodiments, each of the light reflecting structures has a first region and a second region formed by different materials and having the same thickness, wherein a first light reflectivity of the first region is greater than a second light reflectivity of the second region.

In some embodiments, each of the different materials is selected from a group consisting of silver, aluminum, magnesium, and molybdenum.

In some present embodiments, the first region is surrounded by the second region.

In some present embodiments, the second region is divided into two separate regions by the first region.

In some embodiments, a thickness of each light reflecting structure is less than or equal to 100 nm.

In some embodiments, a thickness of the first region is less than or equal to 100nm and greater than or equal to 40 nm.

In some embodiments, each of the light reflecting structures has a third region between the first region and the second region, and for each corresponding one of the pixels, a third light reflectivity of the corresponding one of the third regions is greater than the second light reflectivity and less than the first light reflectivity.

In some present embodiments, the OLED display panel has a resolution greater than 600 pixels per inch (ppi).

In some present embodiments, the light reflecting structures function as anodes in the pixels, and each light reflecting structure is correspondingly covered and sandwiched by two transparent layers. In one embodiment, the transparent layer is an Indium Tin Oxide (ITO) layer.

In some aspects of the present disclosure, a device may have an OLED display panel as described above. In certain embodiments, the device may be a Virtual Reality (VR) device.

These and other aspects of the present disclosure will become apparent from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings, although variations and modifications therein may be effected without departing from the spirit and scope of the novel concepts of the disclosure.

Drawings

The drawings illustrate one or more embodiments of the disclosure and, together with the written description, serve to explain the principles of the disclosure. Wherever possible, the same reference numbers will be used throughout the drawings to refer to similar or like elements of an embodiment, wherein:

fig. 1A is an image display of the OLED display panel according to the present disclosure.

Fig. 1B illustrates a partially enlarged view of fig. 1A.

FIG. 2 illustrates a vacuum deposition process of a light emitting layer of an OLED panel, according to certain embodiments of the present disclosure.

Fig. 3A is a schematic diagram of an OLED display panel according to certain embodiments of the present disclosure, in which a G light emitting structure overlaps an adjacent R light emitting structure.

FIG. 3B is a schematic diagram of an OLED display panel with combined R/G colors according to certain embodiments of the present disclosure.

Fig. 4A is a cross-sectional view of an OLED display panel according to certain embodiments of the present disclosure.

FIG. 4B is a cross-sectional view of a light reflecting structure of an OLED shown in FIG. 4A.

FIG. 4C is a cross-sectional view of the OLED display panel of FIG. 4A, wherein the green (G) pixel organic light emitting structures are shifted and partially overlapped with the red (R) pixel organic light emitting structures.

FIG. 5A illustrates an OLED display panel according to certain embodiments of the present disclosure, wherein each of the light reflecting structures has two regions.

FIG. 5B is a top view of a reflective structure having two regions shown in FIG. 5A.

Fig. 5C shows the OLED display panel in fig. 5A, wherein the green (G) pixel organic light emitting structures are translated and partially overlapped with the red (R) pixel organic light emitting structures.

Fig. 6A is a top view of an OLED display panel with organic light emitting structures and light reflecting structures in two adjacent pixels according to certain embodiments of the present disclosure.

Fig. 6B is a top view of the organic light emitting structures and the light reflecting structures of two adjacent pixels in the OLED display panel according to certain embodiments of the present disclosure, wherein the organic light emitting structures of the green (G) pixels are shifted and partially overlapped with the organic light emitting structures of the red (R) pixels.

Fig. 6C is a top view of the organic light emitting structures and the light reflecting structures of two adjacent pixels in the OLED display panel according to some embodiments of the present disclosure, wherein each light reflecting structure has two regions, and the organic light emitting structures of the green (G) pixels are shifted and partially overlapped with the organic light emitting structures of the red (R) pixels.

FIG. 7 illustrates a plurality of light reflecting structures according to certain embodiments of the present disclosure.

FIG. 8 is a graph illustrating the relationship between the light reflection rate and the thickness of different light reflecting materials in a light reflecting structure of a blue (B) pixel, according to certain embodiments of the present disclosure.

FIG. 9 is a graph illustrating absolute reflectance versus wavelength for various thicknesses of reflective structure material that is silver, in accordance with certain embodiments of the present disclosure.

FIG. 10 is a top view of a reflective surface having three regions, according to certain embodiments of the present disclosure.

Wherein, the reference numbers:

100 images

120 enlarged view angle

200,300,400,400', 500 organic light emitting diode display panel

210,410,510 base material

220 light-emitting layer

230 fine metal shield

235 shield opening

240 vacuum source

310 hole injection layer

310B,310G,310R hole injection layer structure

320 hole transport layer

330 light emitting layer

330B,330G,330R light-emitting structure

330G' expected position

335,360,460,560,660 overlap region

340 yellow light

420,420B,420G,420R,520B,520G,520R,620B,

620G,620R,710,720,730,740,750,760,770,780,790,1000 reflective structure

424,426 transparent layer

430,530 pixel definition layer

440B,440G,440R,540B,540G,540R,640B,640G,640R organic light emitting structure

450 switching electrode

522B,522G,522R,622B,622G,622R, 1022A first region

524B,524G,524R,624B,624G,624R,1024: second region

550 transparent electrode

600 pixel structure

1026 third region

Detailed Description

The following disclosure will now be described more fully with reference to the accompanying drawings, in which some exemplary embodiments are shown. The present disclosure may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. However, these embodiments are provided to assist in a more complete understanding of the present disclosure and to fully convey the scope of the invention to those skilled in the art. Like reference numerals will refer to like elements throughout.

In the context of the present disclosure and in the context of using each term, the term used generally has a meaning in the art. Specific terms used to describe the disclosure are discussed below or are specified elsewhere below to provide additional guidance to the novice in the art for the disclosure. For convenience, certain terms may be labeled prominently, e.g., using italics and/or quotation marks. The use of a label does not have an effect on the scope or meaning of the term itself, which in the same context is still the same regardless of whether a label is used or not. It should be understood that the same thing can be said in more than one way. Thus, alternative language and synonyms may be used for any one or more of the terms discussed herein, which do not have any special meaning and the terms are not set forth or discussed herein. Synonyms for some specific terms are provided herein. One or more synonyms may be used and other synonyms cannot be excluded. Any embodiments used in the present disclosure that include any term discussed herein are illustrative only and are not intended to limit the scope or meaning of the present disclosure or any exemplary term. As such, the present disclosure is not to be limited by the various embodiments described herein.

It will be understood that when an element is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present. As used herein, "connected" may refer to physical and/or electrical connection. Further, "electrically connected" or "coupled" may be such that there are additional elements between the two elements.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a "first element," "component," "region," "layer" or "portion" discussed below could be termed a second element, component, region, layer or portion without departing from the teachings herein.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, including "at least one", unless the content clearly indicates otherwise. "or" means "and/or". As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions integers, steps, operations, elements, components, and/or groups thereof.

Furthermore, relative terms, such as "lower" or "bottom" and "upper" or "top," may be used herein to describe one element's relationship to another element as illustrated. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in one of the figures is turned over, elements described as being on the "lower" side of other elements would then be oriented on "upper" sides of the other elements. Thus, the exemplary term "lower" can encompass both an orientation of "lower" and "upper," depending on the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as "below" or "beneath" other elements would then be oriented "above" the other elements. Thus, the exemplary terms "below" or "beneath" can encompass both an orientation of above and below.

Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present invention and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

As used herein, "about," "approximately," or "substantially" shall have the meaning of substantially plus or minus 20%, more preferably plus or minus 10% or even more preferably plus or minus 5% deviation from the stated value. Given a numerical value of about, it is intended that the terms "about," "approximately," or "substantially" may be inferred without expressly stated.

The term "light reflectance" as used herein, unless otherwise defined, refers to a relative light reflectance using the actual light reflectance of a layer of silver (Ag) having a thickness of 100nm as a reference. It is particularly noted that the actual light reflectance of the silver material layer having a thickness of 100nm is a stable high ratio substantially close to 100%. Thus, using the actual reflectance of a silver material layer having a thickness of 100nm as a reference, "reflectance" as used herein will be substantially similar to the actual reflectance.

The disclosure is described below with reference to the following embodiments in conjunction with the accompanying drawings. In accordance with the purposes of the present disclosure, as embodied and broadly described herein, certain aspects of the present disclosure relate to a light reflecting structure of an OLED display panel having a specially designed light reflecting electrode layer such that each pixel of the OLED display panel has two different light reflection rates on two different areas in the corresponding light reflecting structure.

As discussed above, an OLED display panel, such as an AMOLED display panel, may be used in devices requiring high resolution. Currently, standard AMOLED display panel resolutions may fall in the range of 400-600 pixels per inch (ppi). However, in some cases, the image projected on the AMOLED display panel is magnified and the resolution may be relatively low. For example, fig. 1A illustrates an image 100 displayed by an OLED display panel according to an embodiment of the present disclosure, and fig. 1B illustrates a partially enlarged view of fig. 1A. Specifically, image 100 as shown in fig. 1A is a VR image, wherein VR image 100 is located at a distance of about 20-30cm from the user's eye, and fig. 1B shows a magnified viewing angle of VR image 100, wherein magnified viewing angle 120 is located at a distance of about 6cm from the user's eye. As shown in fig. 1B, the magnified viewing angle 120 of the image 100 appears as a granular network pattern and is visually observable by the human eye. When a user frequently uses a zoom-in function to zoom in a VR image while operating VR, it is necessary to increase the resolution of the OLED display panel to avoid the problem of a noticeable granular mesh pattern.

However, in order to manufacture an OLED display panel having higher resolution, the pixel size of the OLED display panel must be reduced. For example, fig. 2 illustrates a vacuum deposition process of a light emitting layer of an OLED display panel, according to some specific embodiments of the present disclosure. In particular, the vacuum deposition process is a part of the manufacturing process of the OLED display panel. In the process shown in FIG. 2, a light emitting layer 220 (e.g., a pixel layer) is deposited on a substrate 210 by vacuum deposition through a Fine Metal Mask (FMM)230 and a vacuum source 240. As shown in fig. 2, the light emitting layer 220 includes a plurality of RGB color light emitting structures, and the shielding opening 235 of the FMM 230 is aligned with red (R) of the light emitting structures. Therefore, all the light emitting structures of red (R) are formed together in the same vacuum deposition process, and the green (G) light emitting structure and the blue (B) light emitting structure require two additional vacuum deposition processes to be formed.

The vacuum deposition process is performed using the FMM 230 as shown in fig. 2, two main factors are contained within the limits of the vacuum deposition process: (1) the size of the mask opening 235 of the FMM 230, and (2) the alignment of the mask opening 235 of the FMM 230 with a predetermined location of a corresponding light emitting structure in the light emitting layer 220 on the substrate 210. In response to the requirement of the OLED display panel requiring higher resolution, the size of the light emitting structure in the light emitting layer 220 needs to be reduced. The size of the light emitting structure in the light emitting layer 220 is determined by the size of each shielding opening 235 in the FMM 230, and the size of each shielding opening 235 in the FMM 230 is also reduced accordingly. Thus, a slight deviation of the FMM 230 from its intended position during the vacuum deposition process may cause the light emitting structures of one color to be displaced from their respective positions on the substrate 210. Therefore, precise plating film alignment of the light emitting structure in the light emitting layer 220 becomes more difficult.

When a portion of the light emitting structures in the light emitting layer 220 are shifted from their predetermined positions on the substrate 210, the shift of a portion of the light emitting structures from their predetermined positions may overlap with the neighboring light emitting structures. For example, fig. 3A illustrates an OLED display panel according to some embodiments of the present disclosure, wherein a G light emitting structure overlaps an adjacent R light emitting structure. As shown in fig. 3A, the OLED display panel 300 includes a Hole Injection Layer (HIL)310, a Hole Transport Layer (HTL)320, and a light emitting layer 330 (e.g., a pixel layer) including a plurality of light emitting

structures

330R, 330G, and 330B. Specifically, the HIL 310 and the HTL 320 are optional structures, and in certain embodiments, the OLED display panel 300 may include one of the HIL 310 and the HTL 320. As shown in fig. 3A, HIL 310 includes a plurality of

HIL structures

310R, 310G, and 310B corresponding to 330R, 330G, and 330B. Further, the light emitting structures in the light emitting layer 330 are presented in different rows to illustrate green (G) light emitting structures 330G. Among the light emitting structures 330, the blue (B) light emitting structure 330B and the red (R) light emitting structure 330R are correspondingly located at their relative positions. However, the green (G) light emitting structure 330G is shifted to the right from its desired position 330G' (shown in dashed lines), thereby forming an overlap region 335 with the red (R) light emitting structure 330R. The light emitted from the overlap region 335 is a combination of R/G colors, i.e., yellow (Y) 340. FIG. 3B illustrates the combined R/G color light emitted by the OLED display panel according to certain embodiments of the present disclosure, wherein the overlapping area 360 of light emission shows a yellow pattern due to the upward shift of the green (G) light emitting structure.

FIG. 4A illustrates a cross-sectional view of an OLED display panel, in accordance with certain embodiments of the present disclosure. As shown in fig. 4A, the OLED display panel includes a substrate 410, a light-reflecting electrode layer having light-reflecting

structures

420R, 420G, and 420B, a Pixel Definition Layer (PDL)430, a plurality of organic light-emitting

structures

440R, 440G, and 440B, and a conversion electrode 450. The light reflecting electrode layer is disposed on the substrate 410.

As shown in fig. 4A,

light reflecting structures

420R, 420G, and 420B are disposed on a substrate 410. FIG. 4B is a cross-sectional view of the OLED display panel shown in FIG. 4A. As shown in fig. 4B, the light reflecting structure 420 is correspondingly covered and sandwiched by two

transparent layers

424 and 426, thereby forming a sandwich structure. The

transparent layers

424 and 426 may be Indium Tin Oxide (ITO) layers, and each of the

transparent layers

424 and 426 may be relatively thin compared to the light reflecting structure 420, such that the light reflecting rate of the light reflecting structure 420 is not significantly affected by the

transparent layers

424 and 426.

Referring to fig. 4A, PDL 430 is formed on substrate 410 and the light-reflecting electrode layer. The PDL 430 provides a plurality of openings corresponding to the

light reflection structures

420R, 420G, and 420B, and the organic

light emitting structures

440R, 440G, and 440B are formed in the openings and cover the

light reflection structures

420R, 420G, and 420B, respectively. In certain embodiments, each light reflecting structure may be in direct contact with a respective organic light emitting structure. Alternatively, in certain embodiments, there may be other films or layers (e.g., HILs, HTLs, or other layers) between each light reflecting structure and its corresponding organic light emitting structure, such that each light reflecting structure is not in direct contact with its corresponding organic light emitting structure. The transparent electrode 450 is disposed on the PDL 430 and the organic

light emitting structures

440R, 440G, and 440B. Collectively, these structures form a plurality of OLED pixels, with each light reflecting structure serving as the anode of its respective pixel and transparent electrode 450 serving as the cathode of its respective pixel.

As discussed above, when some of the organic

light emitting structures

440R, 440G, and 440B are shifted from their predetermined positions, the partially shifted organic light emitting structures may overlap their neighboring organic light emitting structures. For example, FIG. 4C shows a cross-sectional view of the OLED display panel of FIG. 4A. As shown in fig. 4C, the organic light emitting structure 440G of the green (G) pixel is shifted to the left and partially overlaps the organic light emitting structure 440R of the red (R) pixel, forming an overlap region 460. Further, the transparent electrode 450 in fig. 4C is removed to better illustrate the overlap region 460. The combined light of the R/G colors may cause an unnecessary yellow pattern at an overlap region 460 between the organic

light emitting structures

440R and 440G, as shown in fig. 3B.

In order to solve the problem of unnecessary yellow patterns caused by the offset of the organic light emitting structures, the present disclosure relates to an OLED display panel, wherein each light reflecting structure includes a plurality of regions having different light reflecting coefficients. In particular, the light reflectance of the portion of the first light reflecting region in each light reflecting structure that does not correspond to the overlapping region is greater than the light reflectance of the portion of the second light reflecting region in each light reflecting structure that corresponds to the overlapping region, so that the light reflectance of each pixel corresponding to the second region can be reduced, thereby reducing unnecessary mixed color patterns. In certain embodiments, the difference between the light reflectance of the first area and the light reflectance of the second area in each light reflecting structure is greater than or equal to 1%, such that the human eye can sense the difference in brightness from the respective first and second areas.

FIG. 5A illustrates a cross-sectional view of an OLED display panel with two regions per light reflecting structure, according to certain embodiments of the present disclosure. As shown in fig. 5A, the OLED display panel 500 includes a substrate 510, a reflective electrode layer having a plurality of

reflective structures

520R, 520G, and 520B, a plurality of organic

light emitting structures

540R, 540G, and 540B, and a transparent electrode 550. Specifically, the light reflecting structure 520R has a first region 522R and a second region 524R, the light reflecting region 520G has a first region 522G and a second region 524G, and the light reflecting region 520B has a first region 522B and a second region 524B. Other structures of the OLED display panel 500 include a substrate 510, a PDL 530, organic

light emitting structures

540R, 540G and 540B, and a transparent electrode 550, which have similar structures to the OLED display panel 400, as shown in fig. 4A, and are not described in detail herein.

Fig. 5B is a top view of the light reflecting structure of fig. 5A having two regions. As shown in fig. 5B, the top view of the light reflecting structure 520 is substantially a square structure, and is divided into a first region (M1)522 and a second region (M2)524 surrounding the first region, and the first area ratio M1 of the first region is 80% of the total area of the light reflecting structure 520. In other words, the second area ratio M2 of the second region is 20% of the total area of the light reflecting structure 520. Further, the first light reflectivity of the first region M1 is greater than the second light reflectivity of the second region M2. For example, if the first light reflectivity of the first region M1 is designed to be 100%, the second light reflectivity of the second region M2 must be less than 100%.

As shown in fig. 5A, the PDL 530 provides a plurality of openings at the positions of the respective

light reflecting structures

520R, 520G, and 520B such that the first region M1 and the second region M2 of each light reflecting structure are exposed in the respective openings. In certain embodiments, the first region M1 and the second region M2 of each light reflecting structure are in direct contact with their respective organic light emitting structures. In essence, in certain embodiments, there may be other films or layers (e.g., HIL, HTL, or other layers) between each light reflecting structure and its corresponding organic light emitting structure, such that the first region M1 and the second region M2 of each light reflecting structure are not in direct contact with their corresponding organic light emitting structure. More specifically, fig. 5C is a cross-sectional view of the OLED display panel of fig. 5A, wherein the organic light emitting structure of the green (G) pixel is shifted and partially overlapped with the organic light emitting structure of the red (R) pixel. As shown in fig. 5C, the organic light emitting structure of the green (G) pixel is shifted and partially overlaps the organic light emitting structure of the red (R) pixel, forming an overlap region 560. However, the light reflecting region 520R is divided into a first region 522R and a second region 524R, and the second region 524R is vertically aligned with the overlap region 560. Since the second light reflectance of the second region 524R is less than 100% (relative to the first light reflectance of the first region 522R), the light reflectance of the second region 524R of the R pixel is lower than that of the first region 522R of the R pixel, thereby reducing unnecessary yellow patterns.

In the embodiment shown in fig. 5B, the first area ratio of the first region M1 is 20% of the total area of the light reflecting structure 520. In some embodiments, the first area ratio of the first region M1 and the second area ratio of the second region M2 may be changed. For example, the first area ratio of the first region M1 may be X of the total area of the light reflecting structure 520, where X is greater than or equal to 80% and less than or equal to 90%. In this example, the second area ratio of the second region M2 may be (1-X) of the total area of the light reflecting structure 520.

FIGS. 6A, 6B and 6C illustrate examples of organic light emitting structures and light reflecting structures of two adjacent pixels on an OLED display panel according to certain embodiments of the present disclosure. Specifically, in fig. 6A, 6B, and 6C, two adjacent pixels correspond to an R pixel and a G pixel, respectively, and the

light reflecting structures

620G and 620R are substantially square structures. As shown in fig. 6A, in the pixel structure 600, the organic

light emitting structures

640G and 640R are not shifted from their predetermined positions. Even though some of the micro-overlap regions are interposed between the organic

light emitting structures

640G and 640R, the overlap regions are not aligned with any portion of either of the

light reflecting structures

620G and 620R.

However, the organic light emitting structure 640G is shifted to the left, and in the pixel structure 600' in fig. 6B, the overlap region 660 may be aligned with a portion of the light reflecting structure 620R, a similar example is shown in fig. 4C, and causes an unnecessary yellow pattern as shown in fig. 3B.

In order to solve the unnecessary mixed color pattern caused by the offset of the organic light emitting structure, as shown in fig. 6C, in the pixel structure 600 ″, the light reflecting structure 620R has a first region 622R and a second region 624R. Accordingly, in an example in which the organic light emitting structure 640G is shifted to the left, the overlap region 660 may be aligned with the second region 624R in the light reflecting structure 620R, similar to the example shown in fig. 5C. Since the second light reflectance of the second region 624R is lower than 100% (compared to the 100% light reflectance of the first region 622R), the light reflectance of the R pixel with respect to the second region 624R is smaller than the light reflectance of the R pixel with respect to the first region 622R, so that unnecessary yellow patterns can be reduced.

In the embodiment shown in fig. 6C, the

light reflecting structures

620R and 620G have a square shape, and the first region is surrounded by the second region. In certain embodiments, however, the shape of the light-reflective regions and the arrangement of the first and second regions may vary. For example, the shape of the light reflecting area may be changed based on the pixel shape. Further, the arrangement of the first and second regions may be adjusted based on the light emitting state and/or frequency of the light emitting structure. In certain embodiments, if the higher frequency of the shift of the organic light emitting structure occurs in a particular direction, the second region may be aligned along this particular direction, rather than surrounding the first region.

FIG. 7 illustrates a plurality of light reflecting structures, in accordance with certain embodiments of the present disclosure. In particular, the light reflecting structure 710 is the same or similar to the respective

light reflecting structures

620R and 620G. In contrast, the other

light reflecting structures

720 and 790 are adjusted to have different shapes and/or different arrangements of the first and second regions M1 and M2. In particular, the light reflecting structure 720 remains as a square, but the arrangement of the first region M1 and the second region M2 is changed to a vertical arrangement in which the first region M1 divides the second region M2 into an upper half region and a lower half region, which are separated from each other. The light reflecting structure 730 remains as a square, but the arrangement of the first region M1 and the second region M2 is changed to a diagonal arrangement in which the first region M1 divides the second region M2 into an upper left half region and a lower right half region, which are separated from each other. The light reflection region 740 has a diamond shape, and the first region M1 and the second region M2 are arranged such that the first region M1 is surrounded by the second region M2. The light reflecting structure 750 is also diamond-shaped, and the arrangement of the first region M1 and the second region M2 is changed to a horizontal arrangement in which the first region M1 divides the second region M2 into a left half region and a right half region, which are separated from each other. The light reflection region 760 is also diamond-shaped, and the arrangement of the first region M1 and the second region M2 is changed to an inclined arrangement in which the first region M1 divides the second region M2 into an upper left half region and a lower right half region, which are separated from each other. The light reflecting structure 770 has a hexagonal shape, and the first region M1 and the second region M2 are arranged such that the first region M1 is surrounded by the second region M2. The light reflecting structure 780 is also hexagonal, and the arrangement of the first region M1 and the second region M2 is changed to a horizontal arrangement in which the first region M1 divides the second region M2 into a left half region and a right half region, which are separated from each other. The light reflecting structure 790 is also hexagonal in shape and the arrangement of the first region M1 and the second region M2 is changed to a vertical arrangement in which the first region M1 divides the second region M2 into an upper half region and a lower half region, which are separated from each other. In certain embodiments, the light reflecting structure may also be other shapes, such as rectangular or any other shape.

As discussed above, in each of the light reflecting structures, the first light reflectance of the first region M1 is greater than the second light reflectance of the second region M2, so that the corresponding pixels of the first region corresponding to the first light reflectance are greater than the corresponding pixels of the second region corresponding to the second light reflectance. In certain embodiments, the first region M1 and the second region M2 may be formed of the same material and have different thicknesses such that the light reflectivity of the first region M1 and the light reflectivity of the second region M2 may vary with different thicknesses. Generally, the light reflection rate of the light reflection structure is increased when the thickness of the light reflection structure is increased. In this example, the first thickness of the first region M1 may be greater than the second thickness of the second region M2, such that the first light reflectance of the first region M1 is greater than the second light reflectance of the second region M2. In certain embodiments, the light reflecting material may be a metal material selected from among silver (Ag), aluminum (Al), magnesium (Mg), and molybdenum (Mo).

In certain embodiments, the first region M1 and the second region M2 may be formed of different light reflecting materials and have the same thickness. The different light reflecting materials may have different light reflectivities, and the material for forming the first region M1 may be a material having a high light reflectivity, such that the first light reflectivity of the first region M1 is greater than the second light reflectivity of the second region M2. In certain embodiments, the light reflecting material may be a metal material selected from among silver (Ag), aluminum (Al), magnesium (Mg), and molybdenum (Mo).

FIG. 8 is a graph illustrating the relationship between the reflectivities of different reflective materials of a reflective structure for blue (B) pixels, in accordance with certain embodiments of the present disclosure. Accordingly, table 1 shows a series of examples of different arrangement ratios of the reflective structures of blue (B) pixels according to certain embodiments of the present disclosure. It should be noted that the ratio of light reflecting structures in pixels of the same color should be the same. For example, the ratio of light reflecting structures in blue (B) pixels should be the same. However, the ratio of the light reflecting structures may be the same or different for pixels of different colors. For example, the ratio of the light reflecting structures in the blue (B) pixels may be different from the ratio of the light reflecting structures in the green (G) pixels.

In particular, in embodiment 1, the light reflecting structure is not divided into a plurality of regions (therefore, the area ratio of M1 is 100%), similar to the structure illustrated in fig. 4A. In examples 2, 3, the light reflecting structure was divided into regions M1 and M2, in which the first area ratio M1 of the first region was 80% and the second area ratio M2 of the second region was 20%. In all examples, the light reflecting material used for the first region M1 was silver (Ag), and the thickness of the first region M1 was 100 nm. Accordingly, in example 1, the total light reflectance (i.e., the sum of the products of the area ratio and the light reflectance) was 100%. In embodiment 2, the light reflecting material for the second region M2 was also Ag, and the thickness of the second region M2 was 40 nm. Therefore, the light reflectance of the second region M2 was 83% (point B in fig. 8). Accordingly, in example 2, the total light reflectance (i.e., the sum of the products of the area ratios and the light reflectance) was 96.6% (80% + 100% + 20% + 83%). In example 3, the light reflecting material for the second region M2 was Mg (which had a low light reflecting effect), and the second region M2 had a thickness of 100 nm. Therefore, the light reflectance of the second region M2 is 65% (point C in fig. 8). Accordingly, in example 3, the total light reflectance (i.e., the sum of the products of the area ratios and the light reflectance) was 93% (-80% + 100% + 20% + 65%).

Further, as shown in fig. 8, for each of the light reflecting materials, when the thickness of the light reflecting material is more than 100nm, the light reflection rate thus reaches a stable value, and when the thickness of each of the light reflecting materials is less than 40nm, a large decrease in the light reflection rate is observed (particularly, in the case of Ag, Mg and Mo). Therefore, in certain embodiments, the thickness of the first region M1 is set to be less than or equal to 100nm and greater than or equal to 40nm, so that each light reflecting structure may be relatively thin without sacrificing their light reflectivity.

TABLE 1

It should be noted that in a hypothetical example, the material used in the second region M2 may be a non-reflective material with a reflectivity of 0%. In this example, the total reflectance ratio (i.e., the sum of the products of the area ratios and the reflectances) is 80% (% 80 × 100% + 20% × 0%). The reflective material used in the second region M2 is basically a reflective material having a reflectivity of greater than 0%, and the overall reflectivity is generally greater than 80%. In particular embodiments, for each light reflecting structure, the difference between the first light reflectance of the first region M1 and the second light reflectance of the second region M2 should be greater than or equal to 1% so that the human eye can recognize the difference therebetween.

Still further, in each of the examples shown in table 1, the second region M2 has a light reflectance of less than 100%. In certain embodiments, the light reflectivity of the second region M2 should be no greater than 99% (in other words, at least 1% less than the light reflectivity of the first region M1), so that the light reflectivity of the first region M1 and the second region M2 can be differentiated for human eyes to distinguish the corresponding difference between the light-emitting luminances thereof.

FIG. 9 illustrates absolute reflectance of a reflective material, silver as a reflective structure, as a function of wavelength of light, in accordance with certain embodiments of the present disclosure. Accordingly, table 2 shows the ratio (M1 area ratio of 100%) of the structures of a series of blue (B) pixels (wavelength 460nm) in example 1, wherein the reflective material is silver and has different thicknesses according to certain embodiments of the present disclosure. As shown in fig. 9, when the thickness of the silver layer is increased, the absolute reflectivity R% of the light reflecting structure is increased accordingly. It should be noted that a difference between absolute (actual) reflectance and relative reflectance exists.

TABLE 2

In the examples shown in tables 1 and 2, the absolute reflectance and the relative reflectance of silver at a specific thickness are normalized ratios calculated based on the absolute reflectance (i.e., the actual reflectance) of silver at a thickness of 100 nm. In particular, when the thickness of the first region M1 is 100nm, the relative reflectance of the first region M1 is 100%. In certain embodiments, the thickness of each light reflecting structure is set to 80nm such that the relative reflectivity (99%) and its corresponding absolute reflectivity (92%) are retained at relatively high values. In certain embodiments, the thickness of each light reflecting structure may be less than 80 nm. As discussed above, in a specific embodiment, the thickness of the first region M1 may be set to be less than or equal to 100nm and greater than or equal to 40 nm.

In some of the above-discussed embodiments, the light reflecting structure has two regions including a first region M1 and a second region M2. In certain embodiments, additional regions may be added such that the light reflecting structure has more than two regions. For example, FIG. 10 illustrates a top view of a light reflecting structure having three light reflecting regions, in accordance with certain embodiments of the present disclosure. As shown in fig. 10, the light reflecting structure 1000 is substantially a square structure, which is divided into three regions, including a first region (M1)1022, a second region (M2)1024 surrounding the first region, and a third region (M3)1026 between the first region M1 and the second region M2. The area ratios of the first region M1, the second region M2, and the third region M3 may be relatively adjusted. In certain embodiments, the third light reflectivity of the light reflecting structure 1000 corresponding to the third region M3 is greater than the second light reflectivity of the light reflecting structure 1000 corresponding to the second region M2 and less than the first light reflectivity of the light reflecting structure 1000 corresponding to the first region M1. In certain embodiments, the light reflecting structure may be segmented into more than three regions, and the details of these embodiments will not be described in detail herein.

In certain embodiments, the OLED display panels discussed above may be used to achieve higher resolution. For example, the resolution of the OLED display panel may be greater than 600 ppi. Furthermore, the OLED display panel discussed above can be applied to any device requiring high resolution, such as a VR device.

The foregoing description has been presented only for the purpose of illustrating exemplary embodiments of the present disclosure and is not intended to be exhaustive or to limit the precise forms of the invention disclosed herein. The above teachings may be modified or varied.

The embodiment was chosen and described in order to explain the principles of the disclosure and their practical application to thereby enable others skilled in the art to utilize the disclosure and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present disclosure pertains without departing from its spirit and scope. Accordingly, the scope of the invention is to be determined from the appended claims rather than by the foregoing description and the exemplary embodiments described therein.

Claims

1. An organic light emitting diode display panel, comprising:

a substrate;

a reflective electrode layer disposed on the substrate and having a plurality of reflective structures, wherein each of the reflective structures has a first region and a second region;

a pixel defining layer formed on the substrate and the reflective electrode layer, wherein the pixel defining layer has a plurality of openings corresponding to the reflective structures such that the first region and the second region of each of the reflective structures are exposed in a corresponding one of the openings; and

a plurality of organic light emitting structures correspondingly formed in the openings and covering the light reflecting structures to form a plurality of pixels;

wherein, for each corresponding pixel in the pixels, a first light reflection rate of the corresponding pixel corresponding to the first area is greater than a second light reflection rate of the corresponding pixel corresponding to the second area.

2. The oled display panel of claim 1, wherein the oled display panel has an overall light reflectance greater than or equal to 80%.

3. The oled display panel recited in claim 1, wherein a first area ratio of the first region to a total area of each of the light reflecting structures is X, a second area ratio of the second region to the total area of each of the light reflecting structures is (1-X), and X is greater than or equal to 80% and less than or equal to 99%.

4. The oled display panel of claim 1, wherein a difference between the first light reflectance of the first region and the second light reflectance of the second region is greater than or equal to 1% for each of the light-reflecting structures.

5. The oled display panel of claim 4, wherein the first and second regions are formed of a same material and have different thicknesses for each of the light-reflecting structures such that the first light-reflecting rate of the first region is greater than the second light-reflecting rate of the second region.

6. The oled display panel of claim 5, wherein the material is selected from the group consisting of silver, aluminum, magnesium, and molybdenum, and a first thickness of the first region is greater than a second thickness of the second region.

7. The oled display panel of claim 4, wherein the first and second regions are formed of different materials and have the same thickness for each of the light-reflecting structures such that the first light-reflecting rate of the first region is greater than the second light-reflecting rate of the second region.

8. The oled display panel recited in claim 7, wherein each of the different materials is selected from a group consisting of silver, aluminum, magnesium, and molybdenum.

9. The oled display panel of claim 1, wherein the first region is surrounded by the second region.

10. The organic light emitting diode display panel of claim 1, wherein the second region is divided into two separate regions by the first region.

11. The oled display panel recited in claim 1, wherein a thickness of each of the light-reflecting structures is less than or equal to 100 nm.

12. The oled display panel recited in claim 1, wherein a thickness of the first region is less than or equal to 100nm and greater than or equal to 40nm for each of the light-reflecting structures.

13. The oled display panel of claim 1, wherein each of the light-reflecting structures further has a third region between the first region and the second region, and a third light-reflecting rate of the corresponding pixel with respect to the third region is greater than the second light-reflecting rate and less than the first light-reflecting rate for each corresponding pixel of the pixels.

14. The oled display panel of claim 1, wherein the oled display panel has a resolution greater than 600 ppi.

15. The oled display panel claimed in claim 1, wherein the light-reflecting structures function as anodes of the pixels, and each of the light-reflecting structures is covered and sandwiched by two transparent layers, respectively.

16. The oled display panel recited in claim 15, wherein the transparent layers are ito layers.

17. An apparatus having an organic light emitting diode display panel as claimed in claim 1.

18. The device of claim 17, wherein the device is a virtual reality device.